I fertilize in mid-to-late April with either bone meal, or a fertilizer low in nitrogen, but primarily with a higher phosphate number. I'm speaking of the 3 numbers on fertilizer bags. We call them the NPK (nitrogen, phosphorous, potassium). Fertilizers high in nitrogen will produce lush green foliage, but will not help flowering -- or fruiting (such as on tomatoes) for that matter. Excess nitrogen can also cause bacterial rot. It also depends on where you live. I live in central Florida where there is excess phosphorous in the soil. We have lots of phosphate mines. Also there are lots of houses built from concrete block, covered in concrete "stucco". The phosphates from the concrete leaches into the soil, so around here, we use fertilizers with a low or very low middle number. More than you wanted to know, right?